Astronomy NC 2014

• 1. You will receive a list of unit vocabulary at the top ofevery unit note packet! How you choose to complete the vocabulary is up to you! It should be completed in your science notebook or stored in your binder and will be checked for completion on the day it is due. [10 points] Expect a vocabulary test approximately 1 week after you receive the list.

2. Unit 1The study of stars and space. 3. Big Bang 4. The universe is expanding oHow do we know this? In the late 1920s, Edwin Hubble discovered that All galaxies were redshifted when viewed from Earth. This meant that all galaxies were moving away from Earth and each other, and thus, the universe must be expanding. Learn to annotate! 5. All matter and energy in the universe was once condensed into a single point13.8 bya Moments after the Big Bang, the universe was very hot and dense o Protons, neutrons, and electrons formedo Hydrogen formed o There was enough energy to start nuclear fusion Helium formed 6. Evidence oBackground radiation Space is...space!o There should be no heat at all (0K) o Scientists have measured space; 3K (Background radiation exists) oComposition of matter in the universe74% hydrogen 24% helium 7. Expansion of the Universe 8. A.Electromagnetic Energy 1.2.The sun is the major energy source for weather changes in the atmosphere and many of the changes occurring at Earths surface. Energy from the sun comes in many different wavelengths. 9. The number of wave crests passing any given point in a unit of time High speed = High frequency 10. Study of the properties oflight that depend on wavelength. light given off by stars has many colors The light appears white Spectroscope: Instrument used to break up light from a star into its characteristic colors 11. Continuous Spectrum is an uninterrupted band of color from red to purple 12. Absorption Spectrum appears continuous, but with darklines running through it at various wavelengths Spectra of most stars 13. Emission (you will need to cross out absorption inyour notes) spectrum is a series of bright lines of particular wavelengths depends on the gas that produced them bright lines appear in the exact location as the dark linesthat are produced by the same gas in an absorption spectrum 14. Each element or compound in its gaseous form produce aunique set of spectral lines Spectral lines act as fingerprints used to identify elements present in the stars composition ex) The SUN has thousands of dark lines & more than 60 elements have been identified by matching these lines with those elements known on Earth 15. The Doppler Effect o o oThe change in frequency of a wave an observer relative to its motion Moving toward you: Waves are compressed together Moving away: Waves are stretched 16. Redshift oWhen the light of a distant object (star, planet, etc.) is viewed through a prism, the spectrum is notcontinuous 17. Redshift oWhen the light of a distant object (star, planet, etc.) is viewed through a prism, the spectrum is not continuousoBlack lines appear: Absorption lines oDetermine which elements are presentWhen the object is moving away from us, the absorption lines are shifted toward the red end of the spectrum (stretched): Redshift! 18. Using the spectroscope, astronomers can determine whether a particular object is moving toward Earth or away from Earth 19. Hubbles Law: The further an object is from Earth, the faster it is moving oIf a galaxy is twice as far from Earth as another, it is moving twice as fast 20. Structure of the Sun 21. Our sun is just one of billions of stars in the Milky Way galaxy. Only star whose surface we can study. Through spectroscopic analysis of the sun, scientists know that most of the known elements are found in the sun oHydrogen makes up 74% of the suns massoHelium makes up 24% 22. Sunspots: Dark areas on the sun o ooCool areas The magnetic field breaks through the surface, causing a disruption in heat transfer The number of sunspots varies every 11 years. This is known as the solar cycle. 23. The core oNuclear fusion 24. Life Cycles of Stars 25. A Star is Born 26. A stars life cycle can last billions of years. The following slides describe the general phases in stellar evolution 27. Nebula Dark, cool clouds of interstellar gas and dust. Often referred to as stellar nurseries. Stars begin to form as gas and dust collide. 28. Protostar Developing star Not yet hot enough for fusion reactions (10x106 K)http://seethaler.net/space/protostar.jpeg 29. Main Sequence Star Hydrogen to Helium fusion has begun! The hotter, larger stars burn H2 fastest. This stage makes up 90% of a stars life.http://content4.bestthinking.com/s/1/topics/500/images/3e6daf0-40a3-495c-8006-5da9e7e9b069_972.jpeg 30. Hertzsprung-Russell Diagram E. Hertzsprung and H. Norris Russell studied the relation between the absolute magnitude (or luminosity) and spectral types (or surface temperature) of stars. The diagram showing these two variables is known as HR diagram. The HR diagram represents a major step towards an understanding of stellar evolution. 31. Earths Place in the Universe 32. Universe Our Milky Way Galaxy is one of billions of galaxies in an expanding universe 33. Milky Way Galaxy Our Sun/solar system is one of an estimated 180 billion stars making up this spiral galaxy 34. Our Solar System Earth a small dense rocky planet, one of 8 planets that orbit the sunAND the only one we know of that has LIFE as we know it 35. Models of the Universe A. Geocentric Model 1. About 2000 years ago, the Greek astronomer, Claudius Ptolemy developed a detailed model of the universe based on the idea of revolving spheres. 36. Models of the Universe 2. In this model of the universe, Earth was at the center, and all heavenly bodies moved around Earth in Perfect circles. 37. 3. Ptolemys Geocentric model, as illustrated on the next page, can be summarized as follows: a. Earth is located in the center and does not move. b. The stars are located on a transparent sphere that rotates once each day from east to west around Earth. 38. c.The Sun, the Moon and each planet are carried by separate spheres of different sizes.d.Each planet is located on an epicycle that also rotates. This explained retrograde motion the apparent backward motion of planets. 39. d. This model was accepted for almost 1400 years because itexplained celestial observations made from Earth andseemed obvious.However f.itThe geocentric model does NOT explain terrestrial (Earth) observations such as: 1.The movement/rotation of a pendulums direction.2.The curvature of the paths of projectiles, winds & ocean currents. 40. B. Heliocentric Model In the 1500s, a new model of the universe was proposed in a book by the Polish astronomer Nicholas Copernicus.In this model of the universe, the sun was the center. 2:08 41. Heliocentric Model Copernicus heliocentric model can be summarized as follows: 1. The Sun is located in the center of the system and does NOT move. 2. The stars are located on a stationary/unmoving transparent sphere. The sphere is a great distance from the sun. 3. The planets, including Earth, move in circles around the sun. 4. The Moon moves in a circle around Earth. 5. Earth rotates on its axis from west toward east each day. 42. However.. Copernicus heliocentric model does NOT explain the apparent cyclic variations in the size of the Sun, and the cyclic variation in orbital speeds of the planets. This is because in the heliocentric model, the planets orbit the sun in perfect circles. 43. C. Keplers Heliocentric Model 1. In 1609, Johannes Kepler published a book which included his first 2 Laws of Planetary Motion. These laws explain why the apparent size of the sun changed, and why the speed of a planet changes as it orbits the Sun. 44. a. Keplers First Law The orbit of each planet is an ellipse with the sun at one focus and an imaginary point in space at the other focus. 45. An Ellipse draw the parts in your notes An ellipse looks like an oval, or squashed circle. The longest line drawn from one end of the ellipse (through the center) to the other side is called the major axis. 46. Eccentricity Eccentricity (e) = the out of roundness shape of the ellipse given by the ratio of the distance between the two foci and the length of the major axis. e =distance between foci Length of Major AxisThe eccentricity of a circular orbit is zero, and can range from zero to less than one for an ellipse. 47. 2. Eccentricity d.Relationship: As the distance between the focal points increase, the shape of the ellipse becomes more oval (Circle = 0) 48. B. Keplers Second Law describes the fact that a planet moves fastest in its orbit when it is nearest the Sun.Maximum speed Decreasing speed Area A = Area B = Area CMinimum speed 49. B. Keplers Second Law1. Perihelion= point in orbit nearestto sun2. Aphelion from sun= point in orbit furthest 50. C. Keplers Third Law The further a particular planet is from the sun, the longer its period (time) of revolution. 1. Farther planets have longer orbital paths 2. Farther planets have slower orbital paths 51. D. Sir Isaac Newton 1. Newtons Laws of Gravity First Law a) All objects with mass will be acted on by gravity and will pull all other objects with a certain gravitational force. 52. Newtons Laws of Gravityb) Newtons Second LawThe mass of an object will determine the amount of gravitational force that object possesses. The greater the mass, the greater the gravitational force. 53. Newtons Laws of Gravity c) Third Law The gravitational force between 2 objects changes as the distance between them change. As the distance increases, gravitati onal pull will decrease. 54. 2. Gravity and Inertia 55. a. Newtons Law of Inertia States that a body in forward motion will continue in forward motion unless acted on by an outside force.InertiaGravityStable Orbit 56. B. Gravity and Inertia Inertia causes a planet to move in a straight line. Gravity pulls a planet toward the sun. 57. Rotation The spinning of a celestial body (Earth) on an imaginary axis 58. Rotation A. Earths Direction of Rotation: WEST to EAST 2. Angular Rate of Rotation: THINK one complete rotation a. 360 degrees b. 24 hours Rate = 3600/24 hours = 150/hour 59. B. Effects of Earths Rotation 1. Day and Night 60. B. Effects of Earths Rotation 2.Apparent daily motion of the suna. Earth rotates from WEST to EAST b. Sun appears to move in an arc from EAST to WEST 61. Earth is NOT a perfect sphere. It is an oblate spheroid slightly wider across the equator (due to its rotational spin) Earths axis is not stable. It moves/wobbles (like a top). This is known as precession. Its very slow - 26,000 years to complete one cycle. Within the precession are additional motions known as nutations. These are smaller motions back and forth as the precession occurs. 62. V. Revolution The orbiting of one celestial body around another celestial body. A. Earths Angular Rate of Revolution1. 360 degrees 2. 365 days 3. Rate = 3600/365 days ~ = 10/day 63. B. Effects of Earths Revolution 1. Nighttime constellations change in a yearly cycle. 2. Constellation groups of stars that form patterns of imaginary things such as animals, legendary heroes, and mythological gods 64. 3. Seasons a yearly cycle 65. 5. Seasons of the Year A.Causes: 1.Revolution - Earth revolves around the sun2.TILT - Earth is tilted/inclined on axis 23 1/2o3.Parallelism of Axis - Earths axis always points in the same direction. 66. B. Earths axis is tilted 23.50 relative to the plane of its orbit. Draw and label your diagram according to the diagram at the right. Be sure to name the equator, the Tropic of Cancer and Capricorn and note where we live. 67. C. The apparent path of the sun changes with the seasons and with latitude.N.C. 35.5 degrees North Latitude 68. D. Length of Daylight (duration of daylight) changes with seasons and with latitude. 69. E. Factors affecting Insolation 1. Shape of the Earth (spherical)2. As latitude increases, the angle of insolation decreases, and the intensity of insolation decreases. 70. 3. Season of the Year a.As Earth travels along its orbital path around the sun, the angle of insolation at a given latitude changes with the seasons. This depends on how far a given latitude is from the direct rays of the sun. The direct rays migrate between the Tropic of Cancer (north) and the Tropic of Capricorn (south). 71. 4. Time of Day a.The angle of insolation changes in the course of one day. Maximum intensity occurs at Noon. 72. b. Looking South The shadow of a vertical pole indicates how the angle of insolation changes during the day. The higher/greater the angle of insolation, the shorter the shadow, and the greater the intensity of insolation. 73. VI The Moon A.The moon is a natural satellite of Earth. 1. Luna Latin for moon 2. Diana Roman goddess of the moon 74. B. Physical Properties of the Moon 1. Size a. Diameter: 2160 miles b. Compared to Earth Diameter of Moon = 2160 = 1 Earth 2.80004Gravity a. 1/6 the gravity of Earth b. This is because the Moon has less mass 75. 2. Atmosphere a)The Moon has No atmosphere, so radiation fromsun strong b)Gravity too weak so gases escape into space.c)Without an atmosphere radiation from the sun is INTENSE!d)Frozen water may exist at the Moons polar regions, but none in liquid form 76. 3. Temperatures a. 240oF on the lighted sideb. - 240oF on the far sidec. These large temperature extremes or differences exist because NO atmosphere to transfer heat. 77. 4. The Moons Revolution a. Period of Revolutionb. 1 month OR 29.5 days c. The moon revolves around Earth in an elliptical orbit with the Earth at one focus. d. This causes the moons apparent diameter/size to change in a cyclic manner. 78. 5. Phases of the Moon a.The phases of the moon are caused by the moons revolution around Earth.b.Our Earth view of the changing illuminated part of the moons surface that faces Earth. 79. c. Waning moon - the decrease in light (on the left), away from being a full moon to new moon, is called a. 80. d. waxing moon - as the moon increases towards becoming a full moon. 81. Phase #1 New Moon When the moon is in between the sun and the Earth, we cannot see the moon. This part of the moon is in the shade. 82. 6. Moon Rotation b.c.Does that mean the moon doesn't rotate? YES it does --one rotation for each revolution around Earth! 83. 7. Lunar Eclipse a. An eclipse of the Moon can only take place at full moon and only if the Moon passes through some portion of the earths shadow. The shadow is actually composed of two (2) cone-shaped components, one inside the other. The outer or penumbra shadow is a zone where some portion of the suns rays are blocked. In contrast, the inner or umbra shadow is a region devoid of all direct sunlight. 84. 8. Solar Eclipse a.A solar eclipse occurs when the moon passes directly between the Earth and sun.b.New Moon are the only time solar eclipses can occur. 85. 10. Tides a. Tides are the alternate rising and falling of the sea. b. This is caused by the Moons gravitational pull. c. The rising of tides is affected by the position and distance of moon! d. The period from high tide to high tide is 12 hours and 12 minutes. e. Tides are a CYCLIC